1. package Mouse is 
  2.  
  3.     pragma Pure; 
  4.  
  5.     -- Represents the buttons on a three-button mouse. 
  6.     type Mouse_Button is (Mouse_Left, Mouse_Right, Mouse_Middle); 
  7.  
  8.     -- Returns Mouse_Button 'mb' as a string: "Left", "Right", or "Middle". 
  9.     function To_String( mb : Mouse_Button ) return String; 
  10.  
  11. end Mouse;